UNDERSTANDING KŪPEʻE (NERITA POLITA) GONAD DEVELOPMENT AND DEMOGRAPHY FOR CONTINUED USE AT TWO SITES ON HAWAIʻI ISLAND A THESIS SUBMITTTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI‘I AT HILO IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN TROPICAL CONSERVATION BIOLOGY & ENVIRONMENTAL SCIENCE DECEMBER 2017 Heather Nahaku Kalei Thesis Committee: Marta deMaintenon, Chairperson Kalei Nuʻuhiwa Misaki Takabayashi Keywords: Kūpeʻe, Nerita polita, life histories, length at maturity, population density.
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UNDERSTANDING KŪPEʻE (NERITA POLITA) GONAD DEVELOPMENT AND DEMOGRAPHY FOR CONTINUED USE AT TWO SITES ON HAWAIʻI ISLAND
A THESIS SUBMITTTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF
HAWAI‘I AT HILO IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
Keywords: Kūpeʻe, Nerita polita, life histories, length at maturity, population density.
i
Acknowledgements
My deepest gratitude goes out to all those, who, knowingly or unknowingly stoked my
love for home, and in turn led me to choose a life and career centered around living in ways
which honor my kūpuna. I am grateful for the lessons learned through this thesis journey and the
alternate futures they create.
Mahalo mau a mau to those who have guided this journey, including those who came
before me, my ʻohana, committee members and mentors, and the community we are a part of.
May this work provoke curiosity, inspiration, and action. May it be refined, added to, and one
day rendered obsolete by the wealth of knowledge and understanding.
Amama ua noa!
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Abstract
Kūpeʻe (Nerita polita Linnaeus, 1758) is a cryptic, mostly nocturnal intertidal species of
gastropod mollusc used widely in Hawaiʻi for sustenance and cultural practices. Despite a long
tradition of human interaction with this species, information is generally lacking regarding its
reproductive ecology. Results of this study suggest that male and female individuals do not differ
significantly in size and that the minimum shell length at maturity for both males and females is
14 mm. Mature gonads were present in both sexes throughout the study period, and mating was
documented throughout the same period, suggesting continuous spawning throughout the year.
These results are consistent at both study sites, Kawaihae and Waiuli, Hawaiʻi. Comparison of
population size structure at the study sites with the desirable shell lengths, as denoted by the
Bishop Museum lei collection and modern lei, shows that less than 5% of the population fits into
the desirable size range.
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Table of Contents Acknowledgements .......................................................................................................................... i Abstract ........................................................................................................................................... ii List of Tables ................................................................................................................................. vi List of Figures ............................................................................................................................... vii Introduction ..................................................................................................................................... 1
List of Tables Table 1. Shell length ranges .......................................................................................................... 16
Table 2. Timing of gonad development. ....................................................................................... 18
Table 3. Descriptive analysis of shell lengths by month. ............................................................. 21
Table 4. Comparative shell lengths and densities across sites. ..................................................... 22
vii
List of Figures Figure 1. Study sites at Waiuli and Kawaihae on the Island of Hawaiʻi. ....................................... 8
Figure 2. Male Reproductive Stages. ............................................................................................ 14
vitellogenic) oocytes coupled with inter-connective tissue dominant. Stage 2) Pre-vitellogenic
oocytes dominant, with few vitellogenic oocytes within a fully developed macro-gonad structure.
S1 S3 S4 Figure 2. Male Reproductive Stages. Three of the four common stages were documented. S1: Immature or developing gonad, contains pre-spermatozoa. S2: Not documented in this study – inactive but mature gonad, containing fully formed, but empty gonads. S3: All stages and spermatozoa. S4: Spermatozoa degeneration and cytosis. Magnification 40x.
15
Stage 3) A protracted period from December through August when vitellogenic (mature) oocytes
with large yolk dominant. Stage 4) Oocyte degeneration, cytosis and few pre-vitellogenic
oocytes, occurring from September through November. The mean maximum vitellogenic oocyte
length was 25.08 µm (n=70), with a minimum of 16 µm and maximum of 40 µm. A regression
analysis showed no significant relationship between female shell length and maximum oocyte
length (F=0.16, p=0.692, R-sq(adj) = 0.00%).
Shell Length at Maturity
Across both sites, immature individuals were found up to 13.60 mm shell length, mature
females ranged in shell length from 13.00 mm to 22.25 mm, and mature males ranged from
Figure 3. Female Reproductive Stages. S1: few pre-vitellogenic oocytes with connective tissue. S2: Pre-vitellogenic oocytes dominate. S3: Vitellogenic Oocytes with large yolk dominate. S4: Interstitial space, pre-vitellogenic oocytes, and cytosis. Magnification 40x.
S1
S2
S3
S4
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11.50 mm to 22.50 mm (Figure 4, Table
1). A two-sample T-Test found no
significant difference in mean shell
length between males and females
(T=1.40, p=0.164). However it carries a
low statistical power (21 %), so results
should be interpreted cautiously. Mann-
Whitney Tests found no significant
difference in shell lengths between sites
for males (p=0.1958 adjusted for ties), or
females (p=0.8948).
Sex Ratio
The ratio of females to males is 1.19:1
(147 samples) using data from both sites.
Kawaihae had a higher ratio of males
(1.31:1) and Waiuli had a higher ratio of
females (1.75:1).
Discussion Maturity by Shell Length This is the first documentation of kūpeʻe shell length at
reproductive maturity. It allows for the development of
guidelines for a minimum length at reproductive
maturity. The majority of individuals will be mature at
shell lengths greater than 14 mm (obtained by rounding
SexLocation
MIMFWaiuliKawaihaeWaiuliKawaihaeWaiuliKawaihae
24
22
20
18
16
14
12
10
Shel
l Len
gth
(mm
)
KawaihaeWaiuli
Location
16.5862
17.5434
11.775
10.7583
17.722717.5897
Boxplot of Shell Length (mm)
Figure 5. Boxplot comparison of Kawaihae and Waiuli populations: females, males and immature individuals.
Table 1. Shell length ranges for female, male and immature individuals.
MINIMUM (mm)
MAXIMUM (mm)
FEMALE 13.00 22.25MALE 11.50 22.50IMMATURE 13.60
MIMF
24
22
20
18
16
14
12
10
Sex
Shel
l Len
gth
(mm
)
FIMM
Sex
Boxplot of Shell Length (mm)
Figure 4. Boxplot of shell lengths for sites combined: females, males, and immature individuals.
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13.6 mm up to the nearest integer for ease of general utilization), which establishes a minimum
length under which individuals should not be harvested.
Contrary to many gastropods, kūpeʻe showed no sexual dimorphism; both sexes display a
variety of shell color and pattern, and there is no significant difference in shell length. There is
also no evidence of an uneven ratio of females to males. Because no significant difference was
found between male and female shell lengths, the minimum length of 14 mm for harvest applies
to mature individuals of both sexes.
Reproductive Stages Male individuals were found to have three distinct stages (1) Immature, (3) Mature gonad
and spermatozoa, under gametogenesis, and (4) Mature but post-spawning/degenerating gonads.
Stage (2) Pre-spermatozoan (common to this genus), or regenerative stage might be sufficiently
short to remain undocumented by this study. Females displayed four distinct stages, identified
by the dominance of (1) Pre-vitellogenic oocytes, (2) Vitellogenic oocytes, (3) Degenerating
oocytes and cytosis, (4) Interconnective tissue and pre-vitellogenic oocytes. Immature
individuals of both sexes were identified by having minimal macro-gonad structure, with
immature gametes.
Egg Length Egg length appeared to vary with reproductive stage, increasing with increasing oocyte
generation. An egg in S2 will have a smaller length then those in S3. Oocytes in S3 are also
larger than in post-spawning S4. However, caution must be taken in using a 2D cross-section
measurement of a 3D object because its measurement is subject to the particular angle of
sectioning. For example, a large oocyte could be oriented at its narrowed margin, resulting in an
inaccurate measurement. In an effort to reduce this unequal orientation, multiple measurements
of maximum oocyte length were taken from histologic sections in each individual.
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Spermatophore Transfer Tube As was noted by Iriki (1963) in N. albicilla, kūpeʻe also utilize a
cylindrical spermatophore transfer tube, about 4 mm in length, with a
rounded head at one end and a thin “tag” at the other, extending an
additional 2 mm. The spermatophore transfer tube is conducted by the
cephalic penis during mating, and deposited internally in the female. Use
of a spermatophore transfer tube is quite common in nerites, however, this
is the first such documentation for kūpeʻe.
Timing of Gametogenesis
The results of this histological analysis suggest kūpeʻe are capable of breeding for the
majority of the year. Females undergo active gametogenesis from December through August,
with post-spawned individuals appearing from September to November. Males display similar
pattern: undergoing active gametogenesis from January through September, with a period of
post-spawning degeneration from October through December.
Fecundity Within the range of shell lengths measured in the histological portion of this study
(maximum = 22.50 mm) there appears to be no maximum shell length at which gonads “shut
off”. All mature individuals, both male and female, had active gonads. Oocytes had a maximum
length of 40 µm, and unfortunately unequal histological sectioning prevent this study from
comparing the oocyte count of larger females to smaller females, but it was observed that, in
Developmental Stage Jan Feb Mar Apr May June July Aug Sept Oct Nov DecGametogenesisPost Spawning/DegenerationGametogenesisPost Spawning/Degeneration
FEMALES
MALES
Table 2. Timing of gonad development.
Figure 6. Spermatophore transfer tubes.
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general, larger individuals also had larger sections of macro-gonads (thicker swaths of gonad
across consecutive slides). In many species, female size is directly related to oocyte production,
with larger females producing more oocytes (Harding, Mann, and Kilduff 2007). Future studies
utilizing equivalent histological orientations could be used to better evaluate kūpeʻe fecundity.
Caviats
This study did not directly measure the ratio of gonad to body mass to generate a Gonad
Index by weight, due to the very small weight of the reproductive organs and their attachment to
the gut. Separation of the gonad from the gut for measurement could not be done with reasonable
confidence. However, future studies establishing a gonad index for kūpeʻe would be useful for
management purposes.
Part of the impetus for this thesis investigation was to better understand population sizes
and guidelines for a sustainable harvest. In the absence of density data (now obtained through
this study), coupled with the destructive nature of histology, it was deemed wise to be cautious of
causing harvesting impacts. Therefore, monthly collection was limited to 10 individuals, in
expectation that perhaps 5 of the 10 would be females, able to provide oocyte data. Because of
this limited sample size, these results are subject statistical errors in which a finding of no
significance is falsely accepted and an underlying significant effect is missed.
Annual variability in gonad production There is a need for annual data collection in intertidal species, which have been shown to
experience significant variability in gonad production across annual reproductive seasons
(Dunmore and Schiel 2000). Future studies are necessary to better understand whether the results
of this study period are representative of long-term trends in gametogenesis, and in turn,
potential spawning and shoreline recruitment.
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Chapter 2: Demographics Methods
Within the low intertidal range,
inner and outer transects through kūpeʻe
habitat were identified. Transects were
approximately 1 m apart, and 1 m2 quadrats
were deployed every other meter to record
kūpeʻe abundance, shell length,
composition of the benthos, and invertebrate assemblage.
Results For the period between November 2015 and May 2016 across both sites, 1036 individuals
were sampled. The mean shell length was 14.90 mm, minimum = 4.30 mm, maximum = 23.70
mm. The inter quartile range is 13.30 – 17.00 mm. Mating was seen throughout the study period
(Figure 7).
A Kruskal-Wallis Test found that with sites combined, shell length varied significantly
by month (p < 0.001, H = 44.84 DF = 6). The months with the biggest differences were January
Table 4. Comparative shell lengths and densities across sites.
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Kaneʻohe, is located on the Island of Oʻahu, which has a population of just under 1
million people on an island of about 1500 km2, compared to the Island of Hawaii, which houses
a population of 200,000 people on a land mass of ~10,400 km2 (The United States Census
Bureau 2017). Human development and harvesting impacts have a magnified intensity on Oʻahu.
The Kaneʻohe study site is located within a large protected bay, which is typically prime kūpeʻe
habitat. The lower density in Kaneʻohe may be due to the impacts of coastal development and
intensive harvesting pressure from the relatively larger human population.
All locations in Hawaiʻi have smaller mean shell lengths than were recorded in Kiribati,
which was 22.3 mm (F. R. Thomas 2001), however, Kaneʻohe had the largest mean shell lengths
of the three Hawaiʻi sites. It is possible that larger shell size found in Kiribati can be attributed in
part to the comparatively much lower human population in Kiribati (~110,000 people spread
over 33 atolls) (The World Bank 2017) and much the more extensive nearshore lagoon habitats
of the atolls, coupled with mostly incidental harvesting (a diverse selection of mollusc are
harvested, and kūpeʻe are not the most commonly targeted species).
Densities of Bright vs. Dark Nights He pō hīhīwai.
A night for the hīhīwai.
A gainful night. The hīhīwai are freshwater shellfish. On starry nights, they climb upon the rocks
where they can be seen and gathered.
– ʻŌlelo Noʻeau 903
This ʻōlelo noʻeau speaks to the connection ka poʻe kahiko (meaning “the people of old”)
have observed between hīhīwai (Neritina granosa Sowerby, 1825) and dark nights – because
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nights are most starry when the light of the moon does not block them out. The observational
knowledge captured in this saying provides the bases for investigations into the connection in to
kūpeʻe light sensitivity. An additional parallel between Hawaiian and Western science exists in
that hīhīwai and kūpeʻe are closely related in both Hawaiian epistemology and current
phylogenetic theory. Until recently hīhīwai were classified in the genus Nerita, and although
they now reside in a separate genus, they remain in the same family, Neritidae.
The finding, in this study, of no significant difference between bright (around the full)
and dark (around the new) moons should be interpreted cautiously as the sample size was very
small. Kawelo monitored densities along Kaneʻohe Bay, and found higher densities during dark
nights, ranging from 1.5 – 4.75 kūpeʻe/ m2 as compared to 1.3 – 1.7 kūpeʻe/ m2 during bright
nights (statistical significance unknown). This question of light effecting foraging and
reproductive behaviors may have broader implications for coastal development if it is found that
increased ambient light correlates to decreased densities.
Shoreline Recruitment Kawaihae and Waiuli populations showed significant shell length variability by month,
especially between November, with the highest mean shell length, and January, with the lowest.
This information, coupled with the results of the histological study, which showed active
production of mature gametes from January through August, followed by post-spawning gonad
degeneration from September through December, suggests that, while spawning may occur
throughout the year, a significant spawning and gonad transitional period takes place in the Fall.
Recruits (4 – 10 mm) were found at both sites throughout the study period, indicating that the
degeneration and resting phase does not significantly affect shoreline recruitment.
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Again, recruitment patterns often occur with annual variation, so these findings would
need to be compared with long term monitoring to clarify the timing of events and the intensity
of recruitment (i.e. do these results represent a “high”, “normal” or “low” recruitment, and is
recruitment changing over time).
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Chapter 3: Traditional and Historic Adornment: the Bishop Museum Collection
Background Many forms of guidance exist to interpret the values of a particular culture. One way is
to examine things specified by name. The general word for a shelled animal in Hawaiian is pūpū,
and certain groups of shelled animals, such as kūpeʻe, were specifically named. In fact, many
specific names for kūpeʻe exist, based on their color and pattern. According to Titcomb et al.
(1978), kūpeʻe ula (red) were red; anuenue (rainbow) were red or black striped; palaoa (whale
tooth ivory) were creamy white; ʻeleʻele (black, dark) were black; kaniʻo (vertical stripes) were
black with white streaks; mahiole (warrior’s helmet) were white with red stripes; and puna were
rare (no color description). The rarest and most precious kūpeʻe were saved for aliʻi (royalty)
(Pukui 1986). Such is the case of the kūpeʻe, which were gifted to Queen Kapiʻolani as she
traveled across Hawaiʻi, and were eventually made into a spectacular lei now on display at the
Bernice Pauahi Bishop Museum (BPBM).
Methods Kūpeʻe used for bodily adornment within the collection at the BPBM Ethnology
Department were included in this study. The Museum’s acquisition records for each piece were
obtained. Random shells from each piece were measured, and notes on their adornment type,
shell length, cordage material, the incorporation of other natural materials, and any shell
processing were documented.
Results The BPBM houses many kūpeʻe pieces with unknown acquis ion dates. However, those
acquisitions with known dates, range from “before 1889” through 1932, although it is likely
some are more recent based on more modern cordage materials. The pieces come from many
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sources, including the Queen Liliʻuokalani Collection, the
Kapiʻolani-Kalanianaʻole Collection, the Keʻelikōlani
Collection, the J.S. Emerson Collection, and the Lucy Kaopaulu
Peabody, Edgar and Kalani Henriques Collection. These names
may be familiar to many readers as belonging to aliʻi (royalty)
lineages. Even the pieces that are from the collections of
individuals connected to a specific period in time, do not reliably
have information on shell harvesting locations or dates.
However, these collections are interesting based on the lengths of shells used (indicating a
degree of shell length desirability); the diversity of colors and patterns; the types of processing
done to shells; the varieties of materials used to string shells; as well as the incorporation of other
species in the pieces.
Qualitative Analysis
Shells were made into necklaces, chokers, and bracelets. The collection included pieces
in a range of states – from individual shells without indication of a previous incorporation into a
broader bracelet, necklace, etc., to sets of shells along with the deteriorated material that was
used to hold them together (Figure 10), to fully intact, well preserved
pieces and matched sets.
Colors and Patterns
Shells in the collection displayed many colors and patterns. In
addition to a base color, most shells had checkered/chevron patterns,
spots, and/or stripes. The collection included shells of many base
Figure 11. Anuenue color variation with red and black stripes on white.
Figure X. Potentially psuedo-polymorphic shell patternation unusual in Hawaiʻi.
Figure 10. Bracelet of mahiʻole shells strung on deteriorating silk ribbon.
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colors, including white, black, grey,
yellow, orange, pink, and red. There
are kaniʻo, which are black with
vertical white streaks; anuenue, with
alternating red, black and white
stripes, and mahiʻole, white with red
stripes (Titcomb et al. 1978).
Matching Shell Sizes
Several pieces show incredible
accuracy in matching shell lengths –
containing consecutive identically
sized shells – within a tenth of a
millimeter.
Material Used for Stringing
Although museum records do not
indicate whether the material
currently connecting the shells is original, several material types remaining were frequently used:
silk ribbon, olonā (Touchardia latifolia), and other unknown natural fiber. One piece belonging to
the Queen Liliuokalani Collection used copper wire, bending it to the shape of each shell (Figure
13).
Used in combination with other invertebrates
Figure 13. Copper wire strung bracelet.
Figure 12. N. exuvia coupled with kūpeʻe ʻeleʻele.
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Many pieces included
other invertebrates, some of
which closely resemble kūpeʻe.
One piece includes a shell of
Nerita exuvia Linnaeus, 1758
(Figure 12), which has a central
Indo-West Pacific distribution,
including Indonesia and the Philippines (Frey 2014).
Shell Processing.
Some shells showed signs of
post-processing. The Queen
Liliʻuokalani collection included two
pieces, which appeared to be sanded to
imitate kaniʻo, the white stripe pattern
(Figure 15). Another piece was coated with an orange-red lacquer, which was seen chipping off
at the edges (Figure 16).
Figure 16. This modern piece incorporates both another invertebrate (Turbo petholatus Linnaeus, 1758), as well as a colored finish, which is seen here chipping off.
Figure 15. Black shells sanded to give the appearance of white kaniʻo stripes.
Figure 14. Kūpeʻe palaoa strung with palaoa (whale tooth).
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Of all the pieces, one lei that distinctly stands out includes a ring of palaoa (sperm whale tooth),
and is paired with palaoa, or white, kūpeʻe (Figure 14). Whale palaoa is highly prized and was
fashioned into a variety of adornments, the most incredible of which is the lei niho palaoa, which
is “a hook-shaped ornament made originally from a sperm-whale tooth (palaoa or palaowa) and
suspended by two coils of braided human hair.” (Buck 1959). Palaoa were also fashioned into
more modern hooks, beads for necklaces, as well as carved into detailed imitations of kūpeʻe,
called kūpeʻe palaoa (Pukui 1986). Palaoa adornment denoted the high status of its wearer.
Here, palaoa colored kūpeʻe are fashioned with whale palaoa, perhaps indicating the significance
carried by these kūpeʻe.
Perhaps the most well preserved and diverse piece belonged to Queen Kapiʻolani, wife of
King Kalākaua (Figure 17). This incredible piece displays almost every kūpeʻe color and pattern
type, some that are not described, as well as shells other than kūpeʻe. It is said that the Queen
was gifted individual shells by makaʻāinana (common people) during her travels around the
Hawaiian archipelago. They were later combined into this incredible lei.
Quantitative Analysis Measurements of 208 kūpeʻe were taken from the BPBM collection. The mean shell
length is 21.7 mm, median 21.8 mm. Minimum shell length is 13.5 mm and maximum is 42.0
Figure 17. Queen Kapiʻolaniʻs lei kūpeʻe, containing the largest recorded shell at 42mm.
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mm. The mean length of kūpeʻe recorded in this study is 14.90 mm, compared to 21.7 mm, the
mean shell length from the BPBM collection. A two-sample T-Test comparing mean shell
lengths from the BPBM Collection (n=208) and the Hawaiʻi Island Sites (combined) (n=981)
found a significant difference in means (p<0.001,
T-Value = 18.77).
Desirable Shell Population at Bishop Museum Mean (21.7mm)
Using the mean shell length (21.7 mm) of
the BPBM collection as an indicator of desirable
shell length for adornment, we find that only
0.3% of all Hawaiʻi Island kūpeʻe recorded
during this study had were this length or larger.
Desirable Shell Population at 20mm
If the desirable shell length is reduced to 20mm (an anecdotal harvesting size), less than
5% of the Hawaiʻi Island population fits into this category.
0.3%
99.7%
Kawaihae & Wailuli Population ≤ 21.7mm
Over21.7mm<21.7mm
4.59%
95.41%
Kawaihae & Waiuli Population ≤20mm
≥ 20.0mm <20.0mm
Figure 19. Desirable Shell Length in Shoreline Populations. Less than 1% of the sampled population is equal to or larger than the BPBM mean. Less than 5% of the sampled population is greater than or equal to the anecdotal harvest length of 20mm.
45
40
35
30
25
20
15
10
Bishop Museum Shell Length (mm Kawaihae & Waiuli Shell Length
Comparison of Shell Lengths
Figure 18. Comparing shell lengths from the BPBM collection and the study sites. The BPBM shells are significantly larger.
32
Discussion The BPBM collection provides almost a century of insight into the material use of
kūpeʻe. Their presence in royal collections, and their connection to palaoa, another highly valued
adornment, reaffirms their importance in the Hawaiian cultural view. The collection includes
pieces illustrating great skill in shell selection and adaptation through the use of modern
materials. Several historical museums in Hawaiʻi house kūpeʻe collections. Further studies of
those collections may provide insight to a broader swath of kūpeʻe adornment, and the
prevalence of harvesting larger shell sizes.
It is unlikely that the BPBM mean shell length (21.7 mm) would be found as the mean for
populations in Hawaiʻi today. It is much more likely that shells such as those in the collection, or
those available for commercial sale today, represent the largest individuals in a given population.
Targeting the largest individuals can lead to lower mean shell lengths unless sufficient time for
replenishment is allowed. Future studies should include those aimed at understanding kūpeʻe
growth rate, catch rate, and size structure at a broader set of sites across Hawaiʻi.
Conclusions Climate Change
Human induced climate change is a settled fact (Bernstein et al. 2007), the impacts of
which are far reaching and particularly concerning in lowland, coastal regions (Lathlean,
Seuront, and Ng 2017; C. D. Thomas et al. 2004). Intertidal communities are and will continue to
be affected by accelerated sea level rise (SLR), ocean warming, ocean acidification, and
increased pollution due to ocean of coastal population centers.
The global average for SLR is 3.1 mm/ year (Williams 2013), however, various scenarios
estimate global SLR to increase by 0.3 m to 0.53m by 2050 and 0.75 m to 1.9 m by 2100
33
(Marrack and O’Grady 2014). SLR is a driving factor in coastal erosion, with rates of sandy
beach erosion exacerbated under future scenarios (Zhang, Douglas, and Leatherman 2004). The
ability of sandy beach habitat to migrate, and then for the intertidal ecological community,
including kūpeʻe, to re-establish within that new habitat will be critical in the future.
Predicted reductions in global wind speeds and shifting ocean currents may impact
distribution potential for kūpeʻe, decreasing the ability for remote recruiting sources to reach
previously enriched areas, and making locally driven recruitment even more important. As
previously noted, the specifics of this species’ larval/planktonic stage are unknown, but it is
possible for warming ocean temperatures to affect the seasonal timing, duration, distribution and
resiliency of larva. Warmer ocean temperatures have been linked in Hawaiʻi to shifts in macro-
algae diversity and benthic cover (Cox et al. 2013). Kūpeʻe recruit to micro-algae dominated
substrate. Shifts from micro- to macro-algae dominated low-intertidal regions may decrease
available food sources as well as provide a physical barrier to kūpeʻe travel from beneath the
sand and up onto boulders or limestone substrate for foraging and mating.
Management Strategies Potential strategies to promote a sustainable population:
1. Select for sizes above the size at maturity, 14mm, ensuring the population will
always contain reproducing individuals. It is encouraging that the mean shell
length for both populations are larger than this value.
2. Kūpeʻe have almost continuous breeding potential throughout the year, excluding
the fall. Therefore, there is no particular periods of time when kūpeʻe are
especially vulnerable to harvesting pressure.
34
3. Desirable shell lengths (20 – 25 mm) occur at of less than 1% monitored
populations. It is likely that harvesting these sizes are removing the largest
individuals from the population.
4. Males and females exists in even ratios and similar sizes, so practices of targeting
the largest individuals for harvest do not significantly affect a single sex.
5. Kūpeʻe are a relatively sedentary and predictable species, and are easily
monitored, so if community members or user groups were interested in
understanding localized kūpeʻe populations, including what local abundance and
scarcity look like, it would not be very technically difficult. In addition to not
being difficult, this type of monitoring would greatly help to inform local
harvesting strategies.
6. Kūpeʻe are vulnerable to human caused habitat degradation, such as water
pollution, shoreline hardening, and light and noise pollution.
7. Kūpeʻe are vulnerable to climate change impacts such as sea level rise, shifting
sand regimes, and increases in macro-algae assemblages. Efforts should be made
to model and protect kūpeʻe habitat migration.
Further Studies A substantial need exists to have archipelago-wide kūpeʻe population data. In this very
brief glimpse into the population dynamics occurring between sites on different islands (Hawaiʻi
and Oʻahu) it is clear there is potential for large variations to exist. In addition to population data
is a need for kūpeʻe predation and harvesting data to understand drivers of population reductions.
And if populations are being decreased in predictable ways, such as targeting the largest
individuals, there is a need to understand the role of the largest individuals to the broader
35
population. This touches on fecundity and the role of large females. The people of Hawaiʻi have
a long history of kūpeʻe use, with no indication in the midden record of a decline in use. What
traditional management strategies fostered continued resource abundance through time? How can
they inform human interactions today?
Finally, all of these efforts should be placed into the context, not of previous climate
trends, but of a future of changing climate. Where and how will kūpeʻe habitat change, and what
steps can be taken to ensure those new intertidal habitats are able to sustain life?
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